Field of the Invention
The invention, according to the various embodiments described herein, relates to a measuring bridge which can be used, for example, in a network analyser in order to supply an excitation signal to a device under test and at the same time to supply reflections of the device under test to an electronic measuring device, and a balun which can be inserted into the measuring bridge, wherein the measuring bridge provides a very high bandwidth.
Discussion of the Background
In addition to investigating reflections of a device under test, a measuring bridge can also be used to investigate the transmission behaviour of the device under test more precisely. In this case, a connection of the device under test is connected to a first port of the network analyser, whereas a second connection of the device under test is connected to a second port of the network analyser. An excitation signal is generated in the network analyser and supplied to the device under test at its first terminal. The signal transmitted by the device under test is output, for example, at the second connection, and supplied to the second port of the network analyser. This second port is also connected to a measuring bridge in order to supply the transmitted signal to the electronic measuring device, which preferably measures it according to magnitude and phase. In this context, it is important that the bandwidth of the usable frequency range is as large as possible, extending therefore over several decades, which again requires a measuring bridge which provides a high directivity at low frequencies and also at high frequencies.
A measuring comprises a resistive bridge for a low-frequency range and a hybrid coupler for a high-frequency range, wherein switches are provided to switch between these two units. It is disadvantageous that, as a result of the different component groups which are used for different frequencies, the construction of the measuring bridge is complicated and requires the running of extensive calibration routines.